Macroscopic analysis of polarization characteristics of gas-diffusion electrodes in contact with liquid electrolytes: Part I: First order reactions

In this paper principles of gas-liquid chemical reaction engineering are applied to analyse the current-potential characteristics of gas-diffusion electrodes (GDE) in contact with liquid electrolytes. A macroscopic electrode model is formulated which accounts for mass transfer in the external diffusion films, in the gas layer and in the flooded layer. The set of model equations accounts for material balances, mass transport kinetics and Butler-Volmer polarization kinetics. Several dimensionless parameter groups are introduced which allow a compact reformulation of the proposed model. For first order reactions its solution can be derived analytically. The introduced parameter groups allow a classification of the different operating modes of a GDE, that is, slow reaction, fast reaction and instantaneous reaction.     

分数型布朗运动粒子追踪模型在沿海污染扩散中的应用

传统的Fickian扩散模型已经不再适用于模拟大规模水域表面污染物的扩散。研究人员已观测到了沿海水域地带的non-Fickian扩散现象。研究发现，沿海表层水域的Hurst指数H并不局限于0-1的范围。因此，在分数布朗运动的基础上，引进了加速分数型布朗运动来模拟non-Fickian扩散，从而使表面Hurst指数可以大于1。本文采用一种新型的加速分数型布朗运动的粒子追踪技术，并由此来模拟沿海水域中的non-Fickian传播。对用粒子云来模拟沿海水域中污染物的non-Fickian扩散方法成功地作了研究。比较实际观测的数据和英国HR Wallingford传统的用Fickian扩散模型计算出来的结果，其模拟的结果更胜一筹。     

Solution Algorithm to a Class of Monetary Rational Equilibrium Macromodels with Optimal Monetary Policy Design

In this paper an extended algorithm using well-known solution methods for monetary models characterized by rational expectations and optimal monetary policy design is given. The extension enables first the use of broad dynamic interdependencies within the structural model of the economy, second stochastic shocks on all endogenous variables and third commitment to a policy displaying no time inconsistency problem. All these points are not entirely new, but are seldom included into an operational solution algorithm. Furthermore a computational improvement concerning the splitting process for the stable and unstable part of the solution is proposed.      

Use of Strip-Strip-Block Design for Multi-Stage Processes to Reduce Costs of Experimentation

A strip-strip-block design is proposed for use in investigating the effects of factors, and their interactions, in three-stage industrial processes. Consideration is given, more generally, to the question of how to generate such designs, what theoretical properties they should have, and how to analyze the results of such designs. A case study is used as an illustration.     

Integral controller design based on disturbance cancellation: Partial LTR approach for non-minimum phase plants

For non-minimum phase plants, the loop transfer recovery (LTR) design of integral controllers based on the disturbance cancellation is considered. Since the design requires an unstabilizable extended plant, the standard LTR method cannot be applied. A new partial LTR method is proposed to overcome the difficulty. The target of the proposed design is a fictitious controller including a disturbance estimator based on the measurement of the minimum phase state. It is shown that the Riccati equation including the gain matrix of the disturbance estimator in the target can be used to recover the target feedback property in the output feedback controller. A simple design example is presented to show the effectiveness of the proposed method.     

Superconducting gap function and upper critical field in the presence of inhomogeneous magnetic order

Rare earth ternary superconductors are known to exhibit oscillatory magnetic orders below their superconducting transition temperatures. The study of behaviour of superconducting electrons in an inhomogeneous magnetic field is therefore important for such systems. We report here the results of our theoretical study of superconducting gap function Δ(T) and upper critical fieldH _c2 (T). The results are applied to analyse and explain the variation of Δ(T) andH _c2 (T) in case of NdRh₄B₄.     

用一种全新模式管理水资源的探讨

水资源作为一种短缺的垄断性商品 ,具有明显社会公益属性 ,不能以完全市场经济模式来管理 ,用计划性水权配置有机结合市场性水权交易的新模式来管理更有利于解决我国缺水问题。文章阐述此新模式管理水资源的紧迫性、必要性、可行性及操作性。     

Direct adaptive tuning of robust controllers with guaranteed stability properties

We address the following problem: given a fixed regulator that insures closed-loop stability for a partially known plant, design a mechanism to adaptively tune the controller parameters in order to improve performance. Our main concern is to insure that global _∞-stability of the overall system is preserved. The proposed parameter update law includes a signal normalization [1] and a σ-modification [2]. The condition for global _∞-stability relates the margin of stability of the closed-loop linear system, the speed of adaptation and the size of the residual set for the tracking error.     

Performance analysis of hexagonal cellular networks in fading channels

This paper analyzes the location‐dependent performance metrics of coverage probability and spectral efficiency in hexagonal cellular networks under Rayleigh fading with a general distribution for shadowing and also including two special cases of no shadowing and lognormal shadowing. The effects of system parameters such as frequency reuse factor, transmission probability of base stations, and signal‐to‐interference‐plus‐noise ratio gap from Shannon capacity are accurately characterized. The proposed approach is applied to fractional frequency reuse (FFR) scheme where the impact of FFR on spectral efficiency is evaluated. Numerical results show that (i) in a lognormal‐shadowed Rayleigh fading channel with the shadowing standard deviation of 12 dB, the cell area wide spectral efficiency is degraded by approximately 40% compared with when there is Rayleigh fading without shadowing; (ii) the improvement in spectral efficiency achieved by FFR over the universal frequency reuse increases as the transmission probability increases and the shadowing becomes less severe; and (iii) in Rayleigh fading without shadowing environment where all the base stations are actively transmitting, FFR achieves approximately 20% improvement in spectral efficiency in the cell edge area. Interestingly, this improvement increases to about 30% if a 3‐dB signal‐to‐interference‐plus‐noise ratio gap from Shannon capacity is further accounted. Copyright © 2015 JohnWiley & Sons